[linux-2.6-block.git] / net / netfilter / nf_nat_irc.c

// SPDX-License-Identifier: GPL-2.0-or-later
/* IRC extension for TCP NAT alteration.
 *
 * (C) 2000-2001 by Harald Welte <laforge@gnumonks.org>
 * (C) 2004 Rusty Russell <rusty@rustcorp.com.au> IBM Corporation
 * based on a copy of RR's ip_nat_ftp.c
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/tcp.h>
#include <linux/kernel.h>

#include <net/netfilter/nf_nat.h>
#include <net/netfilter/nf_nat_helper.h>
#include <net/netfilter/nf_conntrack_helper.h>
#include <net/netfilter/nf_conntrack_expect.h>
#include <linux/netfilter/nf_conntrack_irc.h>

#define NAT_HELPER_NAME "irc"

MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>");
MODULE_DESCRIPTION("IRC (DCC) NAT helper");
MODULE_LICENSE("GPL");
MODULE_ALIAS_NF_NAT_HELPER(NAT_HELPER_NAME);

static struct nf_conntrack_nat_helper nat_helper_irc =
	NF_CT_NAT_HELPER_INIT(NAT_HELPER_NAME);

static unsigned int help(struct sk_buff *skb,
			 enum ip_conntrack_info ctinfo,
			 unsigned int protoff,
			 unsigned int matchoff,
			 unsigned int matchlen,
			 struct nf_conntrack_expect *exp)
{
	char buffer[sizeof("4294967296 65635")];
	struct nf_conn *ct = exp->master;
	union nf_inet_addr newaddr;
	u_int16_t port;

	/* Reply comes from server. */
	newaddr = ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3;

	exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
	exp->dir = IP_CT_DIR_REPLY;
	exp->expectfn = nf_nat_follow_master;

	/* Try to get same port: if not, try to change it. */
	for (port = ntohs(exp->saved_proto.tcp.port); port != 0; port++) {
		int ret;

		exp->tuple.dst.u.tcp.port = htons(port);
		ret = nf_ct_expect_related(exp, 0);
		if (ret == 0)
			break;
		else if (ret != -EBUSY) {
			port = 0;
			break;
		}
	}

	if (port == 0) {
		nf_ct_helper_log(skb, ct, "all ports in use");
		return NF_DROP;
	}

	/* strlen("\1DCC CHAT chat AAAAAAAA P\1\n")=27
	 * strlen("\1DCC SCHAT chat AAAAAAAA P\1\n")=28
	 * strlen("\1DCC SEND F AAAAAAAA P S\1\n")=26
	 * strlen("\1DCC MOVE F AAAAAAAA P S\1\n")=26
	 * strlen("\1DCC TSEND F AAAAAAAA P S\1\n")=27
	 *
	 * AAAAAAAAA: bound addr (1.0.0.0==16777216, min 8 digits,
	 *                        255.255.255.255==4294967296, 10 digits)
	 * P:         bound port (min 1 d, max 5d (65635))
	 * F:         filename   (min 1 d )
	 * S:         size       (min 1 d )
	 * 0x01, \n:  terminators
	 */
	/* AAA = "us", ie. where server normally talks to. */
	snprintf(buffer, sizeof(buffer), "%u %u", ntohl(newaddr.ip), port);
	pr_debug("inserting '%s' == %pI4, port %u\n",
		 buffer, &newaddr.ip, port);

	if (!nf_nat_mangle_tcp_packet(skb, ct, ctinfo, protoff, matchoff,
				      matchlen, buffer, strlen(buffer))) {
		nf_ct_helper_log(skb, ct, "cannot mangle packet");
		nf_ct_unexpect_related(exp);
		return NF_DROP;
	}

	return NF_ACCEPT;
}

static void __exit nf_nat_irc_fini(void)
{
	nf_nat_helper_unregister(&nat_helper_irc);
	RCU_INIT_POINTER(nf_nat_irc_hook, NULL);
	synchronize_rcu();
}

static int __init nf_nat_irc_init(void)
{
	BUG_ON(nf_nat_irc_hook != NULL);
	nf_nat_helper_register(&nat_helper_irc);
	RCU_INIT_POINTER(nf_nat_irc_hook, help);
	return 0;
}

/* Prior to 2.6.11, we had a ports param.  No longer, but don't break users. */
static int warn_set(const char *val, const struct kernel_param *kp)
{
	pr_info("kernel >= 2.6.10 only uses 'ports' for conntrack modules\n");
	return 0;
}
module_param_call(ports, warn_set, NULL, NULL, 0);

module_init(nf_nat_irc_init);
module_exit(nf_nat_irc_fini);
Commit	Line	Data
2874c5fd	1	// SPDX-License-Identifier: GPL-2.0-or-later
869f37d8 PM	2	/* IRC extension for TCP NAT alteration.
	3	*
	4	* (C) 2000-2001 by Harald Welte <laforge@gnumonks.org>
	5	* (C) 2004 Rusty Russell <rusty@rustcorp.com.au> IBM Corporation
	6	* based on a copy of RR's ip_nat_ftp.c
869f37d8 PM	7	*/
869f37d8 PM	8
5191d70f AS	9	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
5191d70f AS	10
869f37d8 PM	11	#include <linux/module.h>
	12	#include <linux/moduleparam.h>
	13	#include <linux/tcp.h>
	14	#include <linux/kernel.h>
	15
	16	#include <net/netfilter/nf_nat.h>
	17	#include <net/netfilter/nf_nat_helper.h>
869f37d8 PM	18	#include <net/netfilter/nf_conntrack_helper.h>
	19	#include <net/netfilter/nf_conntrack_expect.h>
	20	#include <linux/netfilter/nf_conntrack_irc.h>
	21
53b11308 FL	22	#define NAT_HELPER_NAME "irc"
53b11308 FL	23
869f37d8 PM	24	MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>");
	25	MODULE_DESCRIPTION("IRC (DCC) NAT helper");
	26	MODULE_LICENSE("GPL");
53b11308 FL	27	MODULE_ALIAS_NF_NAT_HELPER(NAT_HELPER_NAME);
	28
	29	static struct nf_conntrack_nat_helper nat_helper_irc =
	30	NF_CT_NAT_HELPER_INIT(NAT_HELPER_NAME);
869f37d8	31
3db05fea	32	static unsigned int help(struct sk_buff *skb,
869f37d8	33	enum ip_conntrack_info ctinfo,
051966c0	34	unsigned int protoff,
869f37d8 PM	35	unsigned int matchoff,
	36	unsigned int matchlen,
	37	struct nf_conntrack_expect *exp)
	38	{
	39	char buffer[sizeof("4294967296 65635")];
2690d97a DB	40	struct nf_conn *ct = exp->master;
2690d97a DB	41	union nf_inet_addr newaddr;
869f37d8	42	u_int16_t port;
869f37d8	43
869f37d8	44	/* Reply comes from server. */
2690d97a DB	45	newaddr = ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3;
2690d97a DB	46
869f37d8 PM	47	exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
	48	exp->dir = IP_CT_DIR_REPLY;
	49	exp->expectfn = nf_nat_follow_master;
	50
	51	/* Try to get same port: if not, try to change it. */
	52	for (port = ntohs(exp->saved_proto.tcp.port); port != 0; port++) {
5b92b61f PNA	53	int ret;
5b92b61f PNA	54
869f37d8	55	exp->tuple.dst.u.tcp.port = htons(port);
3c00fb0b	56	ret = nf_ct_expect_related(exp, 0);
5b92b61f PNA	57	if (ret == 0)
	58	break;
	59	else if (ret != -EBUSY) {
	60	port = 0;
869f37d8	61	break;
5b92b61f	62	}
869f37d8 PM	63	}
869f37d8 PM	64
b20ab9cc	65	if (port == 0) {
2690d97a	66	nf_ct_helper_log(skb, ct, "all ports in use");
869f37d8	67	return NF_DROP;
b20ab9cc	68	}
869f37d8	69
2690d97a DB	70	/* strlen("\1DCC CHAT chat AAAAAAAA P\1\n")=27
	71	* strlen("\1DCC SCHAT chat AAAAAAAA P\1\n")=28
	72	* strlen("\1DCC SEND F AAAAAAAA P S\1\n")=26
	73	* strlen("\1DCC MOVE F AAAAAAAA P S\1\n")=26
	74	* strlen("\1DCC TSEND F AAAAAAAA P S\1\n")=27
	75	*
	76	* AAAAAAAAA: bound addr (1.0.0.0==16777216, min 8 digits,
	77	* 255.255.255.255==4294967296, 10 digits)
	78	* P: bound port (min 1 d, max 5d (65635))
	79	* F: filename (min 1 d )
	80	* S: size (min 1 d )
	81	* 0x01, \n: terminators
	82	*/
	83	/* AAA = "us", ie. where server normally talks to. */
	84	snprintf(buffer, sizeof(buffer), "%u %u", ntohl(newaddr.ip), port);
5191d70f	85	pr_debug("inserting '%s' == %pI4, port %u\n",
2690d97a DB	86	buffer, &newaddr.ip, port);
2690d97a DB	87
cba81cc4 GF	88	if (!nf_nat_mangle_tcp_packet(skb, ct, ctinfo, protoff, matchoff,
cba81cc4 GF	89	matchlen, buffer, strlen(buffer))) {
2690d97a	90	nf_ct_helper_log(skb, ct, "cannot mangle packet");
6823645d	91	nf_ct_unexpect_related(exp);
cba81cc4	92	return NF_DROP;
b20ab9cc	93	}
2690d97a	94
cba81cc4	95	return NF_ACCEPT;
869f37d8 PM	96	}
	97
	98	static void __exit nf_nat_irc_fini(void)
	99	{
53b11308	100	nf_nat_helper_unregister(&nat_helper_irc);
a9b3cd7f	101	RCU_INIT_POINTER(nf_nat_irc_hook, NULL);
869f37d8 PM	102	synchronize_rcu();
	103	}
	104
	105	static int __init nf_nat_irc_init(void)
	106	{
d1332e0a	107	BUG_ON(nf_nat_irc_hook != NULL);
53b11308	108	nf_nat_helper_register(&nat_helper_irc);
a9b3cd7f	109	RCU_INIT_POINTER(nf_nat_irc_hook, help);
869f37d8 PM	110	return 0;
	111	}
	112
	113	/* Prior to 2.6.11, we had a ports param. No longer, but don't break users. */
e4dca7b7	114	static int warn_set(const char val, const struct kernel_param kp)
869f37d8	115	{
5191d70f	116	pr_info("kernel >= 2.6.10 only uses 'ports' for conntrack modules\n");
869f37d8 PM	117	return 0;
	118	}
	119	module_param_call(ports, warn_set, NULL, NULL, 0);
	120
	121	module_init(nf_nat_irc_init);
	122	module_exit(nf_nat_irc_fini);